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Fiberglass Windows: The Pros and Cons

Fiberglass windows are made from glass fibers flattened into a reinforced mat that's strong enough to rival aluminum, wood, and vinyl windows. The mat is then reshaped to take on any desired shape to produce a lightweight and compact window that's arguably slicker in appearance than other windows.

In this article:

  • Example of a fiberglass window:
    • Pella's fiberglass bow window.
  • The benefits of fiberglass windows.
  • The drawbacks of fiberglass windows.

Pella's Fiberglass Bow Window

Pella is a top manufacturer of windows that offers all types of windows in any frame material including fiberglass. Their fiberglass windows are engineered with five layers, starting with a structural core patented with an interlocking mat, which is then coated with a heat-set resin that's finally baked to keep form. The final product is built to withstand extreme heat and subzero temperatures.

Their fiberglass window types include sliding, casement, awning, fixed, bay & bow, single, and double-hung windows; all of which are Energy Star qualified.

Pella Impervia is the name given to their collection of outstanding fiberglass windows. Their bow window consists of your choice of four to five casements installed side by side and joined together with mullion bars for a seamless look. Their fiberglass finishes include birch and oak that emulate wood. Pella Impervia bow windows are a beautiful and reliable home addition that create enough room for a seat board and a wide unobstructed view of the outside.

The Advantages of Fiberglass Windows

Structural integrity: Fiberglass expands and contracts at a much lower rate than aluminum, and eight times lower than vinyl which means that it won't thermally expand to the point of detaching itself from the surrounding opening of the frame.

Security: The structural integrity and strength of fiberglass windows discourage intruders from breaking and entering, and is the ideal material for windows specialized to withstand hurricane impacts.

Corrosion resistance: If you live on a residential coastline, fiberglass windows remain unaffected by the salt air and high moisture levels.

Good insulation: Fiberglass is definitely a runner up in terms of insulation when compared to other window materials. It is 89% better than aluminum, and can be better than vinyl with properly glazed glass. 

Home resale value: Where vinyl windows fail at raising the asking price of your home, fiberglass succeeds because it is considered more upscale by interested buyers.

Slim designs: Fiberglass is stronger than vinyl and can, in this way, take on a slimmer design for more glass space and a minimal appearance.

Upholds the glass seal: As a result of its structure integrity, fiberglass does not damage the glass seal from thermal expansion.

Repaintable: Unlike vinyl, fiberglass can be repainted at any point during its life.

Darker paint options: Other window frame materials will avoid darker colors because of their high heat conductivity. Fiberglass is a low heat conductor and can, therefore, accommodate dark colors.

Low-maintenance: Just like vinyl, cleaning with water and detergent is all that's required to maintain your fiberglass windows.

Resistance to natural disfigurement: Rotting, warping, cracking, and shrinking are not a problem to fiberglass windows as they resist all weather conditions that could easily damage other window materials

Durability: With some maintenance a fiberglass window can have a longer lifespan than vinyl by up to 38%.

Can emulate wood frame appearance: Fiberglass is much easier to paint than vinyl and can be coated with wood veneer to look like timber while still retaining its own performance qualities.


The Disadvantages of Fiberglass Windows

  • Can be expensive: Fiberglass windows can be more expensive than vinyl by 15-30%.
  • Takes longer to manufacture: Fiberglass requires a larger workforce and a longer length of time to produce the same number of units as other materials because they are custom made, which could slow down the progress of a home's construction.
  • Color fading: Even though they can be repainted at any point in the future, fiberglass windows nonetheless lose some of their colors over time.
  • Lack color variety: A very limited variety of colors can be applied to fiberglass windows. 

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